1. Field of the Invention
The present invention relates to a method for setting a R-P link for data transmission and reception in a mobile communication system, and more particularly, to a method for setting a R-P link in which a base station controller and packet control function (BSC/PCF) manages the status of a packet data serving node (PDSN). The packet data serving node (PDSN) will transmit packet data if a mobile terminal (mobile station) requests packet data service and selects the PDSN to perform the service.
2. Background of the Related Art
FIG. 1 illustrates mobile communication network elements and their structures for packet data service according to the related art. As shown in FIG. 1, the mobile communication network elements include a mobile station (MS) 101 for a user and a base transceiver station (BTS) 102.
The MS 101 is connected with the BTS 102 with radio frequency. The BTS 102 is also connected to a base station controller (BSC)/Packet control function (PCF) 103. The BSC/PCF 103 is then connected to a mobile switching center (MSC)/visitor location register (VLR) 104. The MSC/VLR 104 is subsequently connected to a home location register (HLR) 105. Thus, the mobile communication network can communicate with other communication networks 106 such as PSTN, PCS, public land mobile network (PLMN). The BSC/PCF 103 can be connected with intranet 108, and further connected to Internet through PDSN 107.
In the mobile communication as shown in FIG. 1, if a terminal that provides code division multiple access (CDMA) 2000 packet data service requests packet data service, PDSN (107) determines whether to transmit packet data based on the BSC/PCF 103. In this case, a radio traffic channel and a radio link protocol (RLC) are set between the mobile station 101 and the BSC 103 in a radio frequency. An A8 traffic link that transmits point to point protocol (PPP) link data between the mobile terminal 101 and the PDSN 107 is set between the BSC 103 and the PCF 103. An A10 R-P link that transmits PPP link data between the mobile terminal 101 and the PDSN 107 is set between the PCF 103 and the PDSN 107.
In the above structure, the A8 interface carries a user traffic between the base station 101 and the PCF 103. The A10 interface carries a user traffic between the PCF 103 and the PDSN 107. At this time, examples of the packet data service connection state of the mobile terminal 101 is divided into packet data service active state and packet data service inactive state. The packet data service inactive state means that the mobile terminal 101 cannot obtain packet data service. Once packet data service is activated by packet data call originated from a user of the terminal or other method, the packet data service inactive state is then changed into the packet data service active state. In the packet data service active state, the PPP link is set between the MS 101 and the PDSN 107 and the R-P link is also set between the PCF 103 and the PDSN 107.
The packet data service active state includes a packet active state and a packet dormant state. The packet active state means that the MS 101 occupies a radio traffic channel and sets an R-P link in order to maintain A8 link and transmit and receive packet data. On the other hand, the packet dormant state means that the BSC 103 is out of the control of the MS 101 and a radio traffic channel by releasing a radio channel and A8 link.
FIG. 2 is a flow chart illustrating a related art for setting a R-P link. In a related art IS-2001 standard, PDSN selection algorithm for setting a R-P link manages the whole PDSN list, divides International Mobile Subscriber Identity (IMSI) number (for example, subscriber's phone number) by the number of all the PDSNs, and selects PDSN with the remainder (modulo calculation), thereby trying to set the R-P link. An A11 (interface that carries signaling information between PCF and PDSN) registration request is tried by the selected PDSN.
Referring to FIG. 2, whether a subscriber pertains to any PDSN by performing modulo calculation of all the PDSNs is first determined in step 21. Then the R-P setup for the PDSN to which the subscriber pertains from the list of all the PDSNs is tried in step 22. Thereafter, whether there is a response from the first tried PDSN is determined in step 23. If there is a response from the first tried PDSN, the R-P is set as shown in step 25. If there is no response from the first tried PDSN, the R-P setup for the next PDSN from the list of all the PDSNs is repeatedly tried as shown in step 24.
In more detail, a mobile IMSI number (subscriber's phone number) is divided by the number of all the PDSNs, so as to confirm whether the subscriber pertains to any PDSN, as follows.
PSDN No.=(Mobile IMSI Number) Modulo N
PDSN NumberPDSN IP address0abcd1klmn2opqur......N-1wxyz
If the PDSN number of the subscriber is 0 by the above modulo calculation, the PCF tries to set R-P at PDSN of 0 when a new call originates. As a result, if there is no A11 registration response, i.e., if R-P setup is failed, R-P setup for the next PDSN number of 1 is tried (PDSN No.=(PDSN No.+1) modulo N). However, the aforementioned related art method for setting R-P has several problems. Since the R-P setup is sequentially tried for the PDSNs without managing the status of the PDSNs, the R-P setup time may be delayed if R-P setup for an abnormal PDSN is tried. Furthermore, even in case that the above R-P setup is repeated until the R-P setup for a normal PDSN next to the abnormal PDSN is tried, data transmission may be delayed if the selected PDSN has a great round trip delay (RTD).
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.